Bushfire risk will double if emissions continue to rise

Summer special a firefighting Aircrane helicopter, one of
four here for the season, is unloaded in Canberra yesterday.Photo: Andrew Sheargold

Wendy Frew, Environment ReporterNovember 7, 2006

The state faces a 25 per cent increase in the risk of extreme bushfire by 2050, regardless of any steps taken now to cut greenhouse gas pollution, according to research by Macquarie University.

That risk could increase to between 50 and 100 per cent if greenhouse gas emissions were allowed to increase to the high end of international projections, the researchers found.

An inability to significantly alter the concentration of carbon dioxide in the atmosphere in the next 25 years would mean governments would have to spend significantly more money on managing bushfires. They might also have to consider banning residential development in areas that backed on to major bushland, the researchers said.

"What governments need to be doing is creating buffer zones between the bush and developments, but they are not doing that because they get developers who want to build into that environment," said Andy Pitman, a climate modeller at Macquarie and one of three authors of the report on the effects of climate change on bushfire risk.

The paper by Professor Pitman, Gemma Narisma and Professor John McAneney drew on AC3 supercomputer simulations of Australia's climate future. The simulations looked at bushfire risk in 2050 and 2100 under low and high greenhouse gas pollution.

"We found that under 2050 conditions there was an increase in bushfire risk [in January] of around 25 per cent compared to today, primarily driven by increased temperatures and lower atmospheric humidities," Professor Pitman said.

"Obviously, if you heat and dry the air you are more likely to get a bushfire. What we do in terms of emissions doesn't have an enormous impact on the probable risk of bushfire by 2050 … but by 2100 … there was a radical difference," he said.

With low emissions there was an additional increase in bushfire risk of about 25 per cent, but with high emissions the probabilities were between 50 and 100 per cent for coastal NSW, and more than 100 per cent for coastal Queensland.

Professor Pitman said the probabilities under a high-pollution scenario in 2100 "go through the roof so extensively that we probably won't actually see bushfires then because we will already have completely burned the bush".

Different modelling by other researchers had come up with similar conclusions but the Macquarie research was the first to place specific probabilities on the risk increase.

Yesterday Rural Fire Service and National Parks crews continued to fight a fire in the Blue Mountains National Park, not far from the edge of Warragamba Dam.

The fire, which has been burning for more than 11 days and has burnt out more than 8800 hectares of bushland, has not yet been contained.

About 30 millimetres of rain has fallen over the area, but it has hampered the firefighting because it has made it difficult to drive vehicles into the areas.

The rain was not enough to boost dam levels, the Sydney Catchment Authority said.

HOT NUMBERS

About 5 per cent of Australia's land surface is burned annually, consuming about 10 per cent of net productivity.